It doesn't give me insomnia, but will it give you insomnia? Who knows? Some people report insomnia or stimulation with certain kavas, but it all depends on the person, the kava and other unknown variables.
I've never felt active and stimulated on any kava, not even the cleanest, headiest kavas or anything else.
But that's just me, I can occasionally have weird disjointed sleep, if the kava fucks with my stomach during the night or on the very rare instance that the kava buzz hits me super hard and makes feel truly and completely high.